Immunosuppressive chemoresistance is a major burden in lung cancer. Recent data reveal that long noncoding RNAs (lncRNAs) present in the lung tumor microenvironment are implicated in ...chemoresistant-related immune deregulation, and metastasis but their exact pathogenic role is still unknown. In this study, we investigate the role of lncRNA PCAT-1 in chemoresistant immunosuppression and its involvement in tumor stroma remodeling. Findings reveal PCAT-1 to regulate Kras-related lung chemoresistance through increased expression of the immunosuppressive micrornas miR-182/miR217 in lung tissues, thus promoting a pre-metastatic niche formation and a subsequent increase in lung metastatic burden. Elevated expression of PCAT-1 negative regulates p27/CDK6 expression by inducing G
0
/G
1
cell cycle arrest through AMPK augmentation, contributing to a tumor-promoting status. Furthermore, PCAT-1 triggered fibroblast differentiation followed by CAF/myofibroblast secretion in TME triggering a CD133/SOX2-related stem cell phenotype. Subsequent PCAT-1 knockdown impaired CAF-mediated stromal activation, and reversed chemoresistance and tumor growth
in vivo
. Overall, these findings demonstrate the versatile roles of PCAT-1 in sustaining lung immunosuppressive neoplasia through tumor microenvironment remodeling and provide new opportunities for effective metastasis inhibition, especially in chemoresistant tumors.
KRAS mutations have been recognized as undruggable for many years. Recently, novel KRAS G12C inhibitors, such as sotorasib and adagrasib, are being developed in clinical trials and have revealed ...promising results in metastatic NSCLC. Nevertheless, it is strongly anticipated that acquired resistance will limit their clinical use. In this study, we developed in vitro models of the KRAS G12C cancer, derived from resistant clones against sotorasib and adagrasib, and searched for secondary KRAS mutations as on-target resistance mechanisms to develop possible strategies to overcome such resistance.
We chronically exposed Ba/F3 cells transduced with KRASG12C to sotorasib or adagrasib in the presence of N-ethyl-N-nitrosourea and searched for secondary KRAS mutations. Strategies to overcome resistance were also investigated.
We generated 142 Ba/F3 clones resistant to either sotorasib or adagrasib, of which 124 (87%) harbored secondary KRAS mutations. There were 12 different secondary KRAS mutations. Y96D and Y96S were resistant to both inhibitors. A combination of novel SOS1 inhibitor, BI-3406, and trametinib had potent activity against this resistance. Although G13D, R68M, A59S and A59T, which were highly resistant to sotorasib, remained sensitive to adagrasib, Q99L was resistant to adagrasib but sensitive to sotorasib.
We identified many secondary KRAS mutations causing resistance to sotorasib, adagrasib, or both, in vitro. The differential activities of these two inhibitors depending on the secondary mutations suggest sequential use in some cases. In addition, switching to BI-3406 plus trametinib might be a useful strategy to overcome acquired resistance owing to the secondary Y96D and Y96S mutations.
Individual oncogenic KRAS mutants confer distinct differences in biochemical properties and signaling for reasons that are not well understood. KRAS activity is closely coupled to protein dynamics ...and is regulated through two interconverting conformations: state 1 (inactive, effector binding deficient) and state 2 (active, effector binding enabled). Here, we use 31P NMR to delineate the differences in state 1 and state 2 populations present in WT and common KRAS oncogenic mutants (G12C, G12D, G12V, G13D, and Q61L) bound to its natural substrate GTP or a commonly used nonhydrolyzable analog GppNHp (guanosine-5'-(β,γ)-imido triphosphate). Our results show that GppNHp-bound proteins exhibit significant state 1 population, whereas GTP-bound KRAS is primarily (90% or more) in state 2 conformation. This observation suggests that the predominance of state 1 shown here and in other studies is related to GppNHp and is most likely nonexistent in cells. We characterize the impact of this differential conformational equilibrium of oncogenic KRAS on RAF1 kinase effector RAS-binding domain and intrinsic hydrolysis. Through a KRAS G12C drug discovery, we have identified a novel small-molecule inhibitor, BBO-8956, which is effective against both GDP- and GTP-bound KRAS G12C. We show that binding of this inhibitor significantly perturbs state 1–state 2 equilibrium and induces an inactive state 1 conformation in GTP-bound KRAS G12C. In the presence of BBO-8956, RAF1–RAS-binding domain is unable to induce a signaling competent state 2 conformation within the ternary complex, demonstrating the mechanism of action for this novel and active-conformation inhibitor.
Individual oncogenic KRAS mutants confer distinct differences in biochemical properties and signaling for reasons that are not well understood. KRAS activity is closely coupled to protein dynamics ...and is regulated through two interconverting conformations: state 1 (inactive, effector binding deficient) and state 2 (active, effector binding enabled). Here, we use 31P NMR to delineate the differences in state 1 and state 2 populations present in WT and common KRAS oncogenic mutants (G12C, G12D, G12V, G13D, and Q61L) bound to its natural substrate GTP or a commonly used nonhydrolyzable analog GppNHp (guanosine-5'-(β,γ)-imido triphosphate). Our results show that GppNHp-bound proteins exhibit significant state 1 population, whereas GTP-bound KRAS is primarily (90% or more) in state 2 conformation. This observation suggests that the predominance of state 1 shown here and in other studies is related to GppNHp and is most likely nonexistent in cells. We characterize the impact of this differential conformational equilibrium of oncogenic KRAS on RAF1 kinase effector RAS-binding domain and intrinsic hydrolysis. Through a KRAS G12C drug discovery, we have identified a novel small-molecule inhibitor, BBO-8956, which is effective against both GDP- and GTP-bound KRAS G12C. We show that binding of this inhibitor significantly perturbs state 1–state 2 equilibrium and induces an inactive state 1 conformation in GTP-bound KRAS G12C. In the presence of BBO-8956, RAF1–RAS-binding domain is unable to induce a signaling competent state 2 conformation within the ternary complex, demonstrating the mechanism of action for this novel and active-conformation inhibitor.
The role of KRAS G12C is of particular interest given the promising clinical activity of KRAS G12C-specific inhibitors. This study comprehensively investigated the clinicopathological characteristics ...and prognostic value of KRAS G12C mutation in patients with surgically resected lung adenocarcinoma.
Data were collected on 3828 patients with completely resected primary lung adenocarcinomas who underwent KRAS mutation analysis between 2008 and 2020. The association between KRAS G12C and clinicopathologic characteristics, molecular profiles, recurrence patterns, and postoperative outcome were explored.
Two hundred seventy-five patients (7.2%) were confirmed to harbor a KRAS mutation, of whom 83 (30.2%) had the G12C subtype. KRAS G12C was more frequent in men, former/current smokers, radiologic solid nodules, invasive mucinous adenocarcinoma, and solid predominant tumors. KRAS G12C tumors had more lymphovascular invasion and higher programmed death-ligand 1 expression than KRAS wild-type tumors. TP53 (36.8%), STK11 (26.3%), and RET (18.4%) mutations were the 3 most frequent in the KRAS G12C group. Logistic regression analysis showed patients with KRAS G12C mutation were prone to experience early recurrence and locoregional recurrence. KRAS G12C mutation was found to be significantly associated with poor survival after propensity score matching. Stratified analysis showed that the KRAS G12C was an independent prognostic factor in stage I tumors and part-solid lesions, respectively.
The KRAS G12C mutation had a significant prognostic value in stage I lung adenocarcinomas as well as in part-solid tumors. Furthermore, it exhibited a potentially aggressive phenotype associated with early and locoregional recurrence. These findings might be relevant as better KRAS treatments are developed for clinical application.
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Colorectal cancer (CRC) is a highly prevalent and lethal cancer worldwide. Approximately 45% of CRC patients harbor a gain-in-function mutation in KRAS. KRAS is the most frequently mutated oncogene ...accounting for approximately 25% of all human cancers. Gene mutations in KRAS cause constitutive activation of the KRAS protein and MAPK/AKT signaling, resulting in unregulated proliferation and survival of cancer cells and other aspects of malignant transformation, progression, and metastasis. While KRAS has long been considered undruggable, the FDA recently approved two direct acting KRAS inhibitors, Sotorasib and Adagrasib, that covalently bind and inactivate KRAS G12C . Both drugs showed efficacy for patients with non-small cell lung cancer (NSCLC) diagnosed with a KRAS G12C mutation, but for reasons not well understood, were considerably less efficacious for CRC patients diagnosed with the same mutation. Thus, it is imperative to understand the basis for resistance to KRAS G12C inhibitors, which will likely be the same limitations for other mutant specific KRAS inhibitors in development. This review provides an update on clinical trials involving CRC patients treated with KRAS G12C inhibitors as a monotherapy or combined with other drugs. Mechanisms that contribute to resistance to KRAS G12C inhibitors and the development of novel RAS inhibitors with potential to escape such mechanisms of resistance are also discussed.
Lung cancer remains one of the most dangerous and most common cancers, requiring constant improvement of diagnostic and treatment methods. The genetic heterogeneity of lung cancer forces us to search ...for new therapeutic targets in an attempt to achieve greater effectiveness for certain groups of patients. The purpose of the study was to update current knowledge about lung adenocarcinoma with a mutation in the KRAS gene, to consider new opportunities for personalized treatment of KRAS-mutated NSCLC and to form an image of a Russian patient who is potentially indicated for targeted therapy. Material and methods . A search of available literature sources published in the Pubmed, Cochrane Library, Elibrary database was carried out, publications covering the period from 2008 to 2023 were included. Results . The article discussed molecular genetic testing, including NGS next generation sequencing, and its role in determining the presence of KRAS gene mutations in patients with lung cancer. the effectiveness of targeted drugs, such as Sotorasib and Adagrasib was also discussed. The mechanism of action is aimed at suppressing the activity of the mutant KRAS G12C protein, which can significantly improve patient survival prognosis. We obtained data on the results of testing 935 patients with non-squamous non-small cell lung cancer from various medical centers in Russia. The KRAS gene mutation was identified in 160 (17.1 %) patients, of whom 96 (10.3 %) had KRAS G12C variant. The KRAS mutation was determined by PCR in 44 patients and by NGS (including on the FoundationOne platform) in 111 patients. Clinical characteristics, such as gender, age, smoking status, PD-L1 expression level, presence of co-mutations (TP53, STK11, KEAP1, were largely similar between patients from real-world clinical practice and patients included in the CodeBreak100 study. Conclusion . The research results confirm the high effectiveness of Sotorasib and Adagrasib for patients with the KRAS G12C mutation and open up new prospects in the treatment of lung cancer. The clinical data obtained from Russian patients demonstrate consistency with the patient profile from registration studies of these drugs. This once again demonstrates the need to expand the range of molecular genetic testing for timely identification of this group of patients and prescribing the most effective treatment for them.
KRAS mutation is the most frequent molecular alteration found in advanced NSCLC; it is associated with a poor prognosis without available targeted therapy. Treatment options for NSCLC have been ...recently enriched by the development of immune checkpoint inhibitors (ICIs), and data about its efficacy in patients with KRAS-mutant NSCLC are discordant. This study assessed the routine efficacy of ICIs in advanced KRAS-mutant NSCLC.
In this retrospective study, clinical data were extracted from the medical records of patients with advanced NSCLC treated with ICIs and with available molecular analysis between April 2013 and June 2017. Analysis of programmed death ligand 1 (PD-L1) expression was performed if exploitable tumor material was available.
A total of 282 patients with ICI-treated (in the first line or more) advanced NSCLC (all histological subgroups) who were treated with ICIs (anti–programmed death 1, anti–PD-L1, or anti–cytotoxic T-lymphocyte associated protein 4 antibodies), including 162 (57.4%) with KRAS mutation, 27 (9.6%) with other mutations, and 93 (33%) with a wild-type phenotype, were identified. PD-L1 analysis was available for 128 patients (45.4%), of whom 45.3% and 19.5% had PD-L1 expression of 1% or more and 50%, respectively (49.5% and 21.2%, respectively, in the case of the 85 patients with KRAS-mutant NSCLC). No significant difference was seen in terms of objective response rates, progression-free survival, or overall survival between KRAS-mutant NSCLC and other NSCLC. No significant differences in overall survival or progression-free survival were observed between the major KRAS mutation subtypes (G12A, G12C, G12D, G12V, and G13C). In KRAS-mutant NSCLC, unlike in non–KRAS-mutant NSCLC, the efficacy of ICIs is consistently higher, even though not statistically significant, for patients with PD-L1 expression in 1% or more of tumor cells than for those with PD-L1 expression in less than 1% of tumor cells, and this finding is especially true when PD-L1 expression is high (PD-L1 expression ≥50%).
For patients with KRAS-mutant NSCLC (all mutational subtypes), the efficacy of ICI is similar to that for patients with other types of NSCLC. PD-L1 expression seems to be more relevant for predicting the efficacy of ICIs in KRAS-mutant NSCLC than it is in other types of NSCLC.
Extracranial arteriovenous malformation (AVM) is most commonly caused by a somatic mutation in MAP2K1. We report two patients with vascular anomalies that had an unclear clinical diagnosis most ...consistent with either an AVM or congenital hemangioma. Lesions were cutaneous, reddish‐purple with telangiectasias, present at birth, and had defined borders. Histopathology indicated AVM and both lesions contained somatic KRAS mutations. A rare AVM phenotype exists that shares clinical features with congenital hemangioma.
Mutant KRAS extracranial arteriovenous malformation
During G1-phase of the cell cycle, normal cells respond first to growth factors that indicate that it is appropriate to divide and then later in G1 to the presence of nutrients that indicate ...sufficient raw material to generate two daughter cells. Dividing cells rely on the “conditionally essential” amino acid glutamine (Q) as an anaplerotic carbon source for TCA cycle intermediates and as a nitrogen source for nucleotide biosynthesis. We previously reported that while non-transformed cells arrest in the latter portion of G1 upon Q deprivation, mutant KRas-driven cancer cells bypass the G1 checkpoint, and instead, arrest in S-phase. In this study, we report that the arrest of KRas-driven cancer cells in S-phase upon Q deprivation is due to the lack of deoxynucleotides needed for DNA synthesis. The lack of deoxynucleotides causes replicative stress leading to activation of the ataxia telangiectasia and Rad3-related protein (ATR)-mediated DNA damage pathway, which arrests cells in S-phase. The key metabolite generated from Q utilization was aspartate, which is generated from a transaminase reaction whereby Q-derived glutamate is converted to α-ketoglutarate with the concomitant conversion of oxaloacetate to aspartate. Aspartate is a critical metabolite for both purine and pyrimidine nucleotide biosynthesis. This study identifies the molecular basis for the S-phase arrest caused by Q deprivation in KRas-driven cancer cells that arrest in S-phase in response to Q deprivation. Given that arresting cells in S-phase sensitizes cells to apoptotic insult, this study suggests novel therapeutic approaches to KRas-driven cancers.
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